High temperature lamp



1945- J. w. MARDEN HIGH TEMPERATURE LAMP Filed Feb. 7, 1942 INVENTOR W WATTORNEY Patented Jan. 16, 1945 HIGH TEMPERATURE LAMP John W. Marden,East Grange, N. 5., assignor to Westinghouse Electric & ManufacturingCompany, East Pittsbur- Pennsylvania Pa, a corporation of ApplicationFebruary 7, 1942, Serial No. 429,844

9 (Claims.

This invention relates to electric, lamps and, more particularly, tosuch adapted to operate at very high temperatures by virtue of beingformed,

at least in part, of material which will stand exceedingly hightemperatures without fusing.

The principal object of my invention, generally considered, is theproduction of electric lamps formed, at least in part of material, morerefractory than. quartz and having the ability to emciently transmitdesired radiations.

Another object of my invention. is the production of electric dischargelamps adapted to oper-- ate with more intense arcs than have heretoforebeen possible in quartz, by virtue of being formed, at least in part, ofa material such a fused magnesia or alumina which has a higher meltingpoint than quartz.

further object of my invention is the production of electric dischargelamps consisting of envelopes of quartz or other suitable material withrefractory, light-transmitting means between the electrodes, such as aliner formed of magnesia, for restricting the arc therebetween withoutat the same time melting or otherwise deteriorating.

A still further object of my invention is the provision of dischargelamps each having a bafile or [battles of refractory material, such asmagnesium oxide, to thereby restrict and provide a more intense arc thanis possible with the use of less refractory material, said lam-10s beingadapted to produce radiations, not only from the discharge but fromportions of the bafiie or baiiles' brought to incandescence.

An additional object of my invention is the provision of discharge lampsin which the intermediate portions are formed or refractory materialsuch as fused, transparent magnesia in the form of tubes, the ends ofsaid tubes being closed by the use of graded seals through which leadsfor the associated electrodes pass, said magnesia tubes desirablyproviding a constricted path for the discharge to thereby increase theintensity thereof to the desired point.

Other objects and advantages of the invention relating to the particulararrangement and construction of various parts, will become apparent asthe description proceeds.

Referring to the drawing,

Fig. l is an axial sectional View of an electric discharge lamp formedwith an envelope of quartz having a liner of magnesium oxide, or othersimilar refractory material, for restricting the discharge.

11-11 of Fig. 1 in the direction of the arrows.

Fig. 3 is a view corresponding to Fig. 1 showing a modification in whichthe envelope of the lamp is formed of quartz and a pair of bafiles ofrefractory material are provided, one adjacent each electrode.

Fig. e is a view corresponding to Fig. 3 but showing another form of myinvention in which the entire central portion of the envelope is formedof refractory material such as fused magnesia and the end portions aregraded therefrom to receive the lead-in conductors for the electrodes.

Fig. 5 is a view corresponding to Fig. 3 but showing another form of myinvention in which only one balfie is used and the envelope is short soas to provide a point source of light.

Referring to the drawing in detail, and first considering the embodimentof my invention illustrated in Figs. 1 and 2, there is shown a dischargelamp ii consisting of an envelope l2 of quartz. The envelope iselongated and an intermediate portion thereof is part y closed by aliner it formed of material which efiiciently transmits the desiredradiations, but which is more refractory, that is, has a considerablyhigher melting point than the material of the envelope it. The walls ofthe liner are, therefore, preferably thicker than those of the envelope.One of the most suitable materials for this purpose is pure fused,light-transmitting magnesia, which has a melting point of about -2800 0.Such material is a good transmitter, not only of visible light, but alsoof infra-red and ultra-violet radiations. At the same time it melts atsuch a high temperature that it may be brought to-incandescence andaugment the light by the discharge without deterioration or change inshape. It may be finished, after rough forming from the fused condition,by machinery with specially hardened tools known in the art.

The lamp it may otherwise be constructed like a high intensity mercurydischarge lamp, a globule of mercury being indicated at it. It is notnecessary to have the entire envelope formed of magnesia because thehottest part will be where the liner i3 is positioned, and it is therebypossible to seal the lead-in conductors l5 and 5, having proper sealingcharacteristics, to the ends of the quartz envelope l2 for the supportof the associated electrodes ii and It. The electrodes may be formed oftungsten or other similar material.

Referring now to the embodiment of my in- Fig. 2 is a traverse sectionalview on the line vention illustrated in Fig. 3, the construction theredisclosed is similar to that in Figs. 1 and 2, except that instead of aliner l3, the quartz envelope l2- of the lamp ll has a pair of bailiesl9 and 2| formed of pure fused, light-transmitting, magnesia, like theliner l3 of the preceding embodiment, but shortened axially of theenvelope and provided with restricted apertures 22 and 23 therethroughfor permitting a discharge of small diameter to pass between theelectrodes ll' and i8. Otherwise the construction may be identical withthat of Figs. 1 and 2.

Referring now to the embodiment of my invention illustrated in Fig. 4,there is shown a lamp ll having an envelope l2", the central orintermediate portion of which consists of a tube 24 having a small bore25 and formed of pure fused, light-transmitting, magnesia like the liner13 of Fig. 1. At the ends of this member 24, quartz chambers 26 and 21are provided for the associated electrodes ll and I8, the lead-inconductors 95 and I6" for said electrodes passing through the outer endsof said chambers 26 and 21,

In order to make it possible to seal lead-in conductors of tungsten orother suitable lead material through the outer ends of said chambers,the lead-in receiving portions of the envelope I2 are connected to themagnesia intermediate part 24 by graded or stepped seals, that is, thecomposition of the material of the chambers 26 and 21 may vary inexpansion between the seal material through which the leads pass andmagnesia, so that the segments 28 and 29 are adapted to seal to the endsof the magnesia tube 24 without breaking. while the extreme portions 3|and 32 are adapted to permit the passage of the lead-in conductors Iiiand IS without the formation of cracks. Otherwise, the construction ofthe lamp may correspond with that of known high-intensity mercurydischarge lamps.

Referring now to the embodiment of my invention illustrated in Fig. 5, alamp l I is here disclosed, which may be identical with the lamp H ofthe first embodiment, except that the liner 13 is shortened axially tobe more like one of the bafiies l9 and 2! of the embodiment in Fig. 3,and the envelope I 2 is correspondingly shortened so that the lamp isadapted to act substantially as a point-source of light and thereby besuitable for projection and the like purposes.

Although I prefer the use of pure, fused, lighttransmitting magnesia formaking the intermed ate discharge-engaging or restricting portions ofthe envelope, yet it will be understood that I do not wish to be limitedto such material, as

pure, fused, light-transmitting alumina or other material having similarqualities, insofar as its endurance to heat and ability to transmitdesired radiations is concerned, may be substituted, assuming that itmay be formed into the necessary shapes or associated with a quartz orother suitable envelope for a discharge lamp.

From the foregoing description, it w ll be seen that I have devised animproved lamp particularly adapted for the production of an electricdischarge of very much greater intensity than was heretofore possible,radiations of desired character being produced, not only by thedischarge, but also by the incanuescence of the associated liner,baflie. or baffles. of the selected refractory material, which may serveto correct or modify the characteristics of the generated radiations. Byvirtue of the material selected. the lamp is adapted to efficientlyproduce and emit infra-red and ultra-violet radiations. as well asvisible light.

It will also be understood that, except as here disclosed, suchlamps maybe constructed like high-intensity discharge lamps in which theenvelopes are quartz, that is the processes of exhausting, filling, andother handling during manufacture are similar to those employed in themanufacture of high-intensity mercury discharge lamps having quartzenvelopes. Although preferred embodiments of my invention have beendisclosed it will be understood that modifications may be made withinthe spirit and scope of the appended claims.

I claim:

1. An electric discharge lamp comprising an outer envelope formed inpart of silicious material and in part of pure, fused,light-transmitting magnesia thicker than the silicious material, aplurality of electrodes therein, and leading-in conductors for saidelectrodes passing through said silicious material, that portion of themagnesia therebetween serving to direct and/or constrict an are whenformed between said electrodes.

2. An electric discharge lamp comprising a generally cylindrical outerenvelope formed of quartz, a pair of electrode therein, lead-inconductors for said electrodes passin through said quartz, and aplurality of magnesia baffles, corresponding in size with the interiordiameter of the envelope and each having a relatively small centralaperture, disposed between said electrodes for constricting thedischarge therebetween.

3. An electric discharge lamp comprising a relatively short generallycylindrical outer envelope formed of silica, electrodes disposed thereinand spaced relatively close to one another, and a bafiie of magnesia,corresponding in diameter with the bore of said envelope, provided witha small orifice, and disposed between said electrodes, whereby adischarge therebetween is constricted and a substantially point-sourceof light obtainable.

l. An electric discharge lamp comprising a generally cylindricalenvelope formed in part of silicious material, and in part of a materialof higher melting point than said silicious material and selected fromthe group consisting of pure, fused, light-transmitting materials morerefractory than silica, a pair of electrodes therein, leadin conductorsfor said electrodes passing through said silicious material, and aplurality of baffles of said higher melting point material,corresponding in size with the interior diameter of the envelope, havingrelatively small central apertures, and disposed between said electrodesfor constricting the discharge therebetween.

5. An electric discharge lamp comprising a relatively short generallycylindrical outer envelope formed in part of silicious material, and inpart of a material of higher melting point than said silicious materialand selected from the group consisting of pure, fused,light-transmitting materials more refractory than silica, electrodesdisposed therein and spaced relatively close to one another, and abaffle of said higher melting point material, corresponding in diameterwith the bore of said envelope, provided with an orifice relativelysmall as compared with said diameter, and disposed between saidelectrodes, whereby a discharge therebetween is constricted and asubstantially point-source of light obtainable.

6. An electric discharge lamp comprising a generally cylindrical outerenvelope formed of quartz, a pair of electrodes therein, lead-inconductors for said electrodes passing through said quartz.

and a plurality of alumina baflles, corresponding in size with theinterior diameter of the envelope and each having a central aperturerelatively small with respect to said diameter, disposed between saidelectrodes for constricting the discharge therebetween.

7. An electric discharge lamp comprising an outer envelope formed inpart of silicious material, and in part of a material of higher meltingpoint than said silicious material and selected from the groupconsisting of pure, fused, light-transmitting materials more refractorythan silica, thicker than the silicious material, a plurality ofelectrodes therein, and lead-in conductors for said electrodes passingthrough said silicious material, that portion of the material of highermelting point therebetween serving to direct and/or constrict an arewhen formed between said electrodes.

8. An electric discharge lamp comprising an outer envelope formed inpart of silicious material and in part of pure, fused,light-transmitting alumina thicker than the silicious material, aplurality of electrodes therein, and lead-in conductors for saidelectrodes passing through said silicious material, that portion of thealumina therebetween serving to direct and/or constrict an arc whenformed between said electrodes.

9. An electric discharge lamp comprising a relatively short, generallycylindrical outer envelope formed of silica, electrodes disposed thereinand spaced relatively close to one another, and a baffle of aluminacorresponding in diameter with the bore of said envelope, provided witha small orifice, and disposed between said electrodes, whereby adischarge therebetween is constricted and a substantially point-sourceof light obtainable.

JOHN W. MARDEN.

